<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>

  <script>
    // var username = 'zs'

    // console.log(username)

    // username = 'xw'

    // console.log(username)

    var age = 18, username, test = '测试', address

    console.log(age)
    console.log(username)
    console.log(test)
    console.log(address)
    console.log(qwer)

    
  </script>
</head>
<body>
  
</body>
</html>